The SIV-smm-pbj-14 strain is a unique primate lentivirus that encodes a Nef protein containing an immunoreceptor-based tyrosine activating motif (ITAM). This ITAM activates T-cells through interaction with ZAP-70 tyrosine kinase, a key component of the T-cell receptor complex (TCR). The hypothesis for this proposal is that this Nef-ITAM may activate intracellular signal pathways in dendritic cells, and thereby enhance immune stimulation and antigen presentation. Two Specific Aims address this hypothesis. Aim 1 describes the construction of various plasmid constructs and adenovirus vectors designed to express several forms of Nef-ITAM together with the target antigen, which is the HIV-1 envelope glycoprotein. Aim 2 assesses the potential role of the Nef-ITAM on antigen presentation functions in cultures of human and mouse dendritic cells infected with adenovirus vectors. Additional in vivo experiments in mice with the adenovirus vectors test the effects of the Nef-ITAM on immune responses to the envelope glycoprotein.